Outdoor railing structures, such as handrails for decks and terraces, are constructed of a variety materials. Many manufacturers and builders of railing structures use polyvinylchloride (PVC) and other plastics to form railing components. Plastic materials require less maintenance than wood, and provide exceptional durability in outdoor installations. In a typical plastic railing system, a pair of closed tubular rails (top and bottom rails) extend parallel to one another between vertical posts or columns. The space between the top and bottom rails is occupied by a series of balusters that connect between the rails.
There are certain drawbacks in using closed tubular rails in a railing system. Closed tubular rails are typically connected to balusters by cutting routed openings in the rails and inserting the ends of the balusters into the hollow interior of the rails. The routed openings introduce areas of relative weakness, called “fracture points”, along the span of the rail. This is a significant concern, since the top and bottom rails are the primary load bearing components in the railing structure. Railing systems that are intended for use in residential construction must be tested to ensure that they support minimum load requirements. Load bearing rails that fail to meet the minimum load requirements can not be used for residential construction. Therefore, closed tubular rails with routed openings have certain limitations that may affect whether or not they can be used in a given project.
Structural integrity has been addressed in the past by adding reinforcing members to the railing components. For example, closed tubular rail systems have been installed with aluminum stiffeners inserted in the hollow interior of the rails. Although aluminum stiffeners increase structural integrity, they may not be desirable in every case. Compared to plastic material, aluminum stiffeners are relatively difficult to cut to a specified length. In addition, insertion of stiffeners into plastic railing components adds additional steps to the installation process.
Closed tubular rails also limit the ability to run wires, cables and utility lines along the railing structure. In most instances, the wiring is simply affixed to the exterior of the closed tubular rail. This leaves the wiring visible on the exterior of the railing, which can detract from the appearance of the railing. In addition, the size and shape of the railing may not allow for more than a few wires to be run along the railing. It may be possible to route the wiring through the interior of the closed tubular railing, but this necessitates cutting into the railing to gain access to the interior of the railing. The process of feeding wiring through a closed tubular rail may be further complicated by posts or other components that divide sections of rail and obstruct the hollow interior of the closed rails. Therefore, the process of cutting into an installed railing can require significant time and labor. Cutting through the sides of plastic rails also leaves holes that may detract from the appearance of the railing system.
Known plastic railing systems involve a number of competing interests. Examples of competing interests include the appearance of railing assembly and the ease of installation. It has been found that when an assembly is modified to address one of these objectives, the other objective is sacrificed. This balancing act between appearance and ease of installation is commonly observed with visible hardware. Systems that do not conceal hardware are relatively simple to install, since they usually require fewer components and steps for assembling. In contrast, many known systems that are designed to conceal hardware require the handling of more components, which increase the time and expense for installing the railing assembly.
The goal of improving aesthetic appearance also competes with the goal of providing structural integrity. As noted above, the use of routed openings to connect balusters with railing components provides a neat and virtually seamless appearance. Unfortunately, routed openings can create fracture zones that compromise the structural integrity of the railing system.
Based on the foregoing, there is much room for improvement in existing railing systems. Among other needs, there is a need for railing systems which are more capable of satisfying competing interests.